1. Field of the Invention
Exemplary embodiments of the present invention relates to a display device and a driving method thereof.
2. Discussion of the Background
A display device such as a liquid crystal display (LCD) and an organic light emitting diode (OLED) display generally includes a display panel including a plurality of pixels, a gray voltage generator generating a gray reference voltage, and a data driver generating a plurality of gray voltages by using the gray reference voltage and applying the gray voltage corresponding to an input image signal among the generated gray voltages as a data signal to a data line. Each of the pixels may include a switching element and a plurality of signal lines.
An LCD may include two display panels having a pixel electrode and an opposing electrode, and a liquid crystal layer interposed between the pixel electrode and the opposing electrode. The liquid crystal layer may have dielectric anisotropy. The pixel electrode may be arranged as a matrix and may be connected to a switching element, such as a thin film transistor (TFT), to sequentially receive, row by row, the data voltage. The opposing electrode may be formed on the surface of the display panel and may receive a common voltage Vcom. The pixel electrode and the opposing electrode may be applied with the voltages to generate an electric field through the liquid crystal layer. The intensity of the electric field and transmittance of light passing through the liquid crystal layer may be controlled, thereby obtaining a desired image. The luminance of the image displayed by the pixel of the display device may be changed according to a difference between the voltage of the pixel electrode and a common voltage Vcom of the opposed electrode.
A polarity of the data voltage applied to the pixel electrode or the common voltage Vcom may be inverted for a predetermined number of frames, and this may be referred to as frame inversion driving. However, a common voltage may be changed by various factors such as a kickback voltage, the applied data voltage, or a capacitance change of a liquid crystal capacitor due to temperature changes, a leakage current of the thin film transistor, or a signal delay. For example, if the same image is displayed for a long time, the charges may gather at one side of the pixel electrode or the opposing electrode and a DC bias may be generated, thereby generating afterimages.